女子走高跳における鉛直速度の獲得に影響をおよぼす踏切局面の技術的要因

抄録

　The purpose of this study was to examine the factors that affect the acquisition of vertical velocity at takeoff in the high jump, with a focus on body rotation and body extension. The subjects were 31 female high jumpers (official record: 1.71 ± 0.04 m) who participated in national-level competitions in Japan. We filmed their take-off motions using 2 high-speed cameras at 240 fps and calculated the kinematic data for their center of gravity. Body rotation and body extension were calculated as model angle change and model length change, respectively. The results obtained were as follows:
　1. In the former phase, when the model length was shortened, a vertical velocity of approximately 50% was obtained at takeoff. The rotation of the body contributed greatly to the acquisition of vertical velocity in the former phase, and extension of the body contributed greatly to the latter phase.
　2. Significant positive correlations were found between the vertical velocity at takeoff and the change in vertical velocity in the latter phase and the vertical velocity at the mid-point. The effect of the correlation was large between the vertical velocity at takeoff and the change in vertical velocity in the latter phase.
　3. Significant correlations were found between the vertical velocity at the mid-point and horizontal velocity and model angle at touchdown. In addition, a significant correlation was found between the vertical velocity at the mid-point and the model angle at the mid-point.
　4. No significant correlation was found between the change in vertical velocity in the latter phase and the body extension parameters in the latter phase. When the model angle exceeded vertical in the latter phase, the acquisition of vertical velocity by rotation and extension of the body became smaller. Therefore, not only the magnitude and speed of body extension but also the direction of extension influenced the acquisition of vertical velocity in the latter phase.
　These results suggest that obtaining a large vertical velocity in the latter phase leads to the generation of a large vertical velocity at takeoff, which usually determines performance in the high jump.